Lattice Framework Research Articles

FiberSim: A flexible open-source model of myofilament-level contraction

FiberSim is a flexible open-source model of myofilament-level contraction. The code uses a spatially explicit technique, meaning that it tracks the position and status of each contractile molecule within the lattice framework. This allows the model to simulate some of the mechanical effects modulated by myosin-binding protein C, as well as the dose dependence of myotropes and the effects of varying isoform expression levels. This paper provides a short introduction to FiberSim and presents simulations of tension-pCa curves with and without regulation of thick and thin filament activation by myosin-binding protein C. A myotrope dose-dependent response as well as slack/re-stretch maneuvers to assess rates of tension recovery are also presented. The software was designed to be flexible (the user can define their own model and/or protocol) and computationally efficient (simulations can be performed on a regular laptop). We hope that other investigators will use FiberSim to explore myofilament level mechanisms and to accelerate research focusing on the contractile properties of sarcomeres.

Fermi Surface Mapping and the Nature of Charge-Density-Wave Order in the Kagome Superconductor CsV3Sb5

The recently discovered family of AV$_3$Sb$_5$ (A: K, Rb Cs) kagome metals possess a unique combination of nontrivial band topology, superconducting ground states, and signatures of electron correlations manifest via competing charge density wave order. Little is understood regarding the nature of the charge density wave (CDW) instability inherent to these compounds and the potential correlation with the accompanying onset of a large anomalous Hall response. To understand the impact of the CDW order on the electronic structure in these systems, we present quantum oscillation measurements on single crystals of CsV$_3$Sb$_5$. Our data provides direct evidence that the CDW invokes a substantial reconstruction of the Fermi surface pockets associated with the vanadium orbitals and the kagome lattice framework. In conjunction with density functional theory modeling, we are able to identify split oscillation frequencies originating from reconstructed pockets built from vanadium orbitals and Dirac-like bands. Complementary diffraction measurements are further able to demonstrate that the CDW instability has a correlated phasing between neighboring V$_3$Sb$_5$ planes. These results provide critical insights into the underlying CDW instability in AV$_3$Sb$_5$ kagome metals and support minimal models of CDW order arising from within the vanadium-based kagome lattice.

Thermally Activated P2‐O3 Mixed Layered Cathodes toward Synergistic Electrochemical Enhancement for Na Ion Batteries

AbstractLayer‐structured oxide cathodes have a lot of phases, which can be varied depending on Na ion contents and finally determine their electrochemical properties. Therefore, the off‐stoichiometry of layer‐structured oxides with the Na ions may differentiate not only their capacities but also the cyclic stabilities, kinetics, and so on, highlighting the importance of Na ion content. However, Na2CO3 tends to be irreversibly formed on surface by making use of the Na ions lost from the lattice. Thereby, the O3 phase with stoichiometric Na content changes into the off‐stoichiometric P2 phase bringing about significant disadvantages. To address this issue, a thermal activation process is suggested to simultaneously decompose Na2CO3 into electrochemically active Na ions and modulate the off‐stoichiometric P2 phase into the stoichiometric O3 phase. This study indicates that minimizing the loss of Na ions and maintaining the lattice framework with higher contents of Na ions during the synthesis of Na‐incorporating layered cathodes should be a key toward attaining electrochemical superiority.

Insights into the Enhanced Structural and Thermal Stabilities of Nb-Substituted Lithium-Rich Layered Oxide Cathodes.

Lithium-rich manganese-based layered oxides (LLOs) are considered to be the most promising cathode materials for next-generation lithium-ion batteries (LIBs) for their higher reversible capacity, higher operating voltage, and lower cost compared with those of other commercially available cathode materials. However, irreversible lattice oxygen release and associated severe structural degradation that exacerbate under high temperature and deep delithiation hinder the large-scale application of LLOs. Herein, we propose a strategy to stabilize the layered lattice framework and improve the thermal stability of cobalt-free Li1.2Mn0.53Ni0.27O2 by doping with 4d transition metal niobium (Nb). Detailed atomic-scale imaging, in situ characterization, and DFT simulations confirm that the induced strong Nb-O bonds stabilize the oxygen lattice framework and restrains the fracture of TM-O bonds, thereby inhibiting the release of lattice oxygen and the continuous migration of TM ions to the lithium layer during the cycle. Furthermore, Nb doping also promotes the surface rearrangement to form a Ni-enrichment layered/rocksalt heterogeneous interface to enhance surface structural stability. As a result, the Nb-doped material delivers a capacity of 181.7 mAh g-1 with retention of 85.5% after 200 cycles at 1C, extraordinary thermal stability with a capacity retention of 80.7% after 200 cycles at 50 °C, and superior rate capability.

Set-Valued T-Translative Functions and Their Applications in Finance

A theory for set-valued functions is developed, which are translative with respect to a linear operator. It is shown that such functions cover a wide range of applications, from projections in Hilbert spaces, set-valued quantiles for vector-valued random variables, to scalar or set-valued risk measures in finance with defaultable or nondefaultable securities. Primal, dual, and scalar representation results are given, among them an infimal convolution representation, which is not so well known even in the scalar case. Along the way, new concepts of set-valued lower/upper expectations are introduced and dual representation results are formulated using such expectations. An extension to random sets is discussed at the end. The principal methodology consisted of applying the complete lattice framework of set optimization.

Yttrium Vanadium Oxide-Poly(3,4-ethylenedioxythiophene) Composite Cathode Material for Aqueous Zinc-Ion Batteries.

The development of metal ion-intercalated active materials for excellent electrochemical performance in rechargeable aqueous zinc-ion batteries (AZIBs) is challenging. The structure instability and intrinsic electrostatic repulsion of the lattice framework cause structural breakdown and low-rate performance. In response to these problems, yttrium vanadium oxide-poly(3,4-ethylenedioxythiophene) (PEDOT@YVO) composite is reported as stable cathode material for AZIBs. The introduction of PEDOT in YVO nanorods improves the crystalline structure with an enlarged interplanar lattice spacing of 3.4 Å. The PEDOT@YVO composite electrode demonstrates effective electric conductivity and a higher initial specific capacity of 308.5mAhg-1 than that (125.5mAhg-1 ) of the pure YVO at 0.2 C rate. It also features a long-term stable discharge-charge cycle performance of 4000 cycles with a capacity retention of 79.2% at 1C rate, better than YVO (29.4mAhg-1 ). The oxygen vacancies and improved electrical conductivity of the composite account for the invigorated electrochemical performance. Consequently, this work reveals another avenue for constructing unique electrodes to enhance the electrochemical properties of AZIBs.

Robust Ultralong Lead Halide Perovskite Microwire Lasers.

Hybrid organic-inorganic lead halide perovskite microwires are potential building blocks for realizing on-chip integrated optoelectronic devices. However, the length-controllable synthesis of one-dimensional hybrid perovskite microwires has been rarely reported, especially the ones with lengths in the millimeter scale. Herein, methylammonium lead bromide (MAPbBr3) and formamidinium lead bromide (FAPbBr3) micro and milliwires are demonstrated using single-crystal PbBr2 microwires synthesized via template-free solution-phase growth as the lattice framework. Following the PbBr2 template, the as-converted perovskite microwires possess controllable lengths ranging from tens to thousands of micrometers. In addition, Fabry-Perot (FP) lasing was realized in both MAPbBr3 and FAPbBr3 microwires, attesting to their excellent crystal quality and the efficient optical confinement of the natural cavity. These unique properties result in the first demonstration of FP perovskite microwire lasers with submillimeter lengths. More interestingly, the microwire lasers show excellent photostability under repetitive pulsed laser excitation for over 8 × 106 cycles. Such findings demonstrate that the solution-converted hybrid lead bromide microwires have excellent optoelectronic performances promising for practical applications, and the size controllability indicates that this novel fabrication process may be feasible for large-scale industrial production.

Weak anionic ligands controlled synthesis of ZnII/CdII coordination polymers based on N-(4-pyridylmethyl)-l-threonine

Four new coordination polymers based on N-(4-pyridylmethyl)-l-threonine (HL), {[Zn(L)(HCOO)](H2O)}n (1), {[Cd(L)(HCOO)](H2O)}n (2), {[Zn(L)(H2O)2](ClO4)(H2O)}n (3), and {[Cd(L)(H2O)2](ClO4)(H2O)}n (4) have been prepared and structurally characterized by X-ray crystallography. Coordination polymers 1–4 crystallize in the uniform space group orthorhombic P212121. Coordination polymers 1 and 2 display two-dimensional lattice frameworks, while 3 and 4 are one-dimensional chain motifs. Interestingly, formate anions can easily coordinate to metal ions in coordination polymers 1 and 2, while perchlorate anions lead to lower dimension of the coordination assemblies in coordination polymers 3 and 4 with the lattice counter ions. And hydrogen bonding interactions play important roles for the formation and stabilization of these three-dimensional supramolecular networks. Furthermore, the thermal stability, and photoluminescence properties have been investigated.

Thermoelectric Properties of Strained β-Cu2Se.

In recent years, the high-temperature phase of Cu2Se, namely, β-Cu2Se, has attracted increasing attention due to its outstanding thermoelectric efficiency. The Cu ions in β-Cu2Se show a distinct ion-liquid behavior between the framework of a Se ion lattice. Many experimental operations may lead to a discrepancy in the lattice structure. Experimentally synthesized β-Cu2Se was p-type, and a thermoelectric device needs both p-type and n-type materials with a close figure of merit. Studying the effect of strain and the possibility of n-type β-Cu2Se is essential. Utilizing first-principles calculations and molecular dynamics simulations, we investigate the thermoelectric performance of strained β-Cu2Se. The results show that the n-type β-Cu2Se can exhibit superior zT values like the p-type one. Applying compressive strain is an effective way to promote the power factor. The tensile strain will lead to a low lattice thermal conductivity and thus boost the p-type zT values. The predicted maximum zT values for n-type and p-type β-Cu2Se can reach 1.65 and 1.71 at 800 K, respectively. Considering the fact that applying strain is challenging in experiments, we propose a feasible strategy to manipulate the lattice structure and carrier type: doping halogen elements. Our results provide a guide for Cu2Se-based thermoelectric devices.

High‐Performance Cathode Materials for Potassium‐Ion Batteries: Structural Design and Electrochemical Properties

Due to the obvious advantage in potassium reserves, potassium-ion batteries (PIBs) are now receiving increasing research attention as an alternative energy storage system for lithium-ion batteries (LIBs). Unfortunately, the large size of K+ makes it a challenging task to identify suitable electrode materials, particularly cathode ones that determine the energy density of PIBs, capable of tolerating the serious structural deformation during the continuous intercalation/deintercalation of K+ . It is therefore of paramount importance that proper design principles of cathode materials be followed to ensure stable electrochemical performance if a practical application of PIBs is expected. Herein, the current knowledge on the structural engineering of cathode materials acquired during the battle against its performance degradation is summarized. The K+ storage behavior of different types of cathodes is discussed in detail and the structure-performance relationship of materials sensitive to their different lattice frameworks is highlighted. The key issues facing the future development of different categories of cathode materials are also highlighted and perspectives for potential approaches and strategies to promote the further development of PIBs are provided.

Trajectory planning for vehicle collision avoidance imitating driver behavior

To ensure that autonomous vehicles satisfy the requirements of the traffic environment, vehicle driving ability, and desired driver experience during obstacle avoidance, this paper proposes a trajectory planner that considers three aspects: driving passability, regional safety, and driving acceptance. Multiresolution state lattices and Bézier curve fitters are applied to a state lattice framework to generate candidate obstacle avoidance trajectory clusters. Trajectory evaluation is then carried out in the above three aspects by using trajectory passability, safety and driver behavior proximity, and a trajectory evaluation function is designed to evaluate and screen trajectory clusters. The trajectory passability is checked by the vehicle motion capability set, which is established based on the vehicle dynamics model. The trajectory safety is evaluated by the potential field function between the fitted trajectory and the vehicle driving environment boundary with consideration of the inevitable collision state. The parameters of the vehicle motion state for the fitted trajectory are matched with the driving data of real drivers with different driving styles to evaluate the proximity between the trajectory and driver behavior. The rationality and effectiveness of different driving styles of trajectory planners are verified by vehicle tests under different vehicle velocities and different obstacle disturbances.

Van der Waals electride: Toward intrinsic two-dimensional ferromagnetism of spin-polarized anionic electrons

Discoveries of two-dimensional (2D) magnetism originated from confined atomic layers in van der Waals (vdW) crystals provide an interesting arena for elucidating its fundamentals and enrich magneto-electric and quantum properties. However, a material that exhibits intrinsic 2D magnetism of interstitial electrons occupying layered space, as a root system of magnetic vdW crystals, remains obscure. In this work, 2D ferromagnetic vdW electride, [RECl]2+·2e− (RE = Y and La) is reported with perfectly isolated ferromagnetic 2D blocks encompassing quasi-atomic electron layers. The ferromagnetism of the vdW electride with Curie temperature of 100 K originates from the spin-polarized quasi-atomic electrons with a substantial moment up to ∼0.91 Bohr magneton, which behave as magnetic elements in paramagnetic lattice framework. Invariable ferromagnetism at the monolayer limit strongly supports the 2D ferromagnetism of quasi-atomic electrons. These findings expand the variety of 2D magnetic crystals, providing a promising platform to study the emergent magnetism of low-dimensional electron phases.

A Polymorphic FeS2 Cathode Enabled by Copper Current Collector Induced Displacement Redox Mechanism.

In this contribution, we fabricated a composite consisting of two polymorphs of FeS2, pyrite (P-FeS2) and marcasite (M-FeS2), for high-performance Li-FeS2 battery. A series of electrochemical, microscopic, and spectroscopic characterizations indicate that the introduction of metastable M-FeS2 into P-FeS2 enables the four-electron reduction between FeS2 and lithium to generate Fe and Li2S, providing a high specific capacity of 894 mAh/g with specific energy over 1300 Wh/kg. Moreover, it is verified that the electrochemical irreversibility of this composite toward lithium storage is mainly rooted in the shuttle effect, caused by the elemental sulfur which is inevitably produced during the oxidation process of Li2S and Fe. To tackle this issue, copper (Cu) current collector is adopted to chemically immobilize the soluble lithium polysulfides and fundamentally alter the reaction pathway. It is shown that compared with Fe, Li2S prefers to react with Cu current collector to generate Cu2S through the thermodynamically facile displacement reaction mechanism benefiting from the similar lattice framework between Cu2S and Li2S. Such displacement reaction without lattice reconstruction renders the composite superior rate capability (∼730 mAh/g@2 A/g) and long lifespan (89.7% capacity retention after 3200 cycles). Present work allows for the fabrication of high-performance electrodes based on metal chalcogenides.

Enhanced activity of Pd/α-MnO2 for electrocatalytic oxygen evolution reaction

This work describes the application of α-MnO2 and Pd/α-MnO2 as electrocatalysts in the oxygen evolution reaction (OER). Characterization data revealed that the Pd2+ precursor has been oxidized during the synthesis, and the resulting Pd4+ ions have unprecedently replaced the lattice framework Mn3+ ions of α-MnO2. Furthermore, formation of PdO nanoparticles was also observed. Lower OER overpotential at j = 10 mA cm−2 (636 mV) was obtained for Pd/α-MnO2 in relation to α-MnO2 (700 mV), what is in alignment with the lower charge transfer resistance of Pd/α-MnO2 (4.9 kΩ cm2) compared to α-MnO2 (10.4 kΩ cm2). Lower Tafel slope (73 mV dec−1) and higher TOF (2.87 × 10−4 s−1) at overpotential of 350 mV was obtained for Pd/α-MnO2 in relation to α-MnO2 (Tafel of 77 mV dec−1 and TOF of 1.94 × 10−4 s−1), indicating a faster electron transfer kinetics promoted by Pd. Pd/α-MnO2 was stable at j = 14 mA cm−2 for 6 h.

High performance anode for sodium-ion batteries: Calcium pre-intercalated layered vanadium oxide/carbon composite

Sodium ion batteries (SIBs) are considered as a promising candidate in the field of large-scale power grids and power storage, owing to their abundant reserves and low price. As a promising intercalated SIBs electrode, vanadium-based compounds have multiple oxidation states, rich coordination polyhedron structure and open lattice frameworks. But those materials are prone to occur the irreversible electrochemical reactions and produce metastable structural materials in the process of electrochemical reaction, resulting in a rapid decrease in capacity. Herein, a novel bilayer-structured vanadium oxide (CaV8O20·3H2O)/Carbon composite material with high specific capacity and long cycling life was synthesized. The CaV8O20·3H2O in this research has overcome the shortcomings of most vanadium-based electrode materials. In the ex-situ mechanism of this study, it was proved that the insertion of calcium ions can effectively maintain the stability of the interplanar spacing of the material and carry out sufficient redox reactions. Combined with the results of electrochemical performance comparison and mechanism analysis, a uniform carbon coating can improve the electrochemical stability and specific capacity of CaV8O20·3H2O by increasing the conductivity of the material and inhibiting adverse side effects. The reported V-based carbon composite anode material exhibited a remarkable electrochemical property with a capacity of 0.2 A g−1 and the capacity retention rate was 92.7% after 200 cycles, and the capacity retention rate was 72% after 450 cycles at a current density of 5.0 A g−1. The novel pre-intercalation model may provide a new perspective for the development of vanadium-based materials in SIBs.

Novel Chain and Ribbon ZnO Nanoporous Crystalline Phases in Cubic Lattice

The chain‐ and ribbon‐like structural hierarchies are used to design two nanoporous polymorphs composed of only four‐member and six‐member rings of ZnO as primary building blocks in cubic lattice frameworks. Specifically, the bottom‐up polymeric assembly of these small simple clusters into high cubic symmetric phases is considered, with energetic, dynamic, and mechanical stabilities proven by density‐functional‐based calculations. Both phases are rivaling with those of known cage‐like nanoporous polymorphs in many porous characteristics while preserving an intrinsic wide bandgap from ZnO tetragonal bonding. Furthermore, the design scheme is feasible to apply with different morphology motifs or extend to more cluster prototypes and materials.

Modelling and deploying multi-energy flexibility: The energy lattice framework

• New multi-energy lattice framework to model multi-energy systems (MES) flexibility. • Categorization of physical and market/regulatory flexibility features. • Two-step methodology to deploy MES flexibility for short-term operational planning. • Simultaneous participation in energy and frequency control markets. • Multi-energy lattice framework demonstrated on the Milan district heating system. This work proposes a novel modelling framework and an associated optimization methodology for short-term operational planning to deploy multi-energy system (MES) flexibility, with application to district energy systems and participation in energy and frequency control ancillary services (FCAS). In this paper, the proposed flexibility framework, based on the concept of multi-energy lattice , models a MES by several energy layers, each one associated with a specific energy carrier. The identified energy layers are linked by specific conversion nodes associated with coupling devices that operate across several energy carriers. After illustrating in detail the main features of the multi-energy lattice methodology and, particularly, how it enables to clearly describe and quantify how flexibility arises from both single-layer and cross-layer energy balancing, different features of the concept of multi-energy flexibility are defined and discussed. An associated operational optimization methodology to deploy multi-energy flexibility in a market environment is then introduced. This methodology is based on a two-step mixed integer linear programming approach, namely, (i) definition of a multi-energy baseline to cope with the energy demand across multiple energy vectors and (ii) identification of flexibility margins and economic convenience to offer different FCAS by deploying multi-energy flexibility. The multi-energy lattice concept is then demonstrated on the Milan district heating system. This MES plant exploits its flexibility for participation in multiple FCAS markets besides day-ahead energy trading, and it is shown how the proposed methodology is able to optimize the flexibility arising from different devices and optimally combine these contributions across multiple energy layers for business case purposes, in line with the general theory of the multi-energy lattice.

Modeling of the tension stiffening behavior and the water permeability change of steel bar reinforcing concrete using mesoscopic and macroscopic hydro-mechanical lattice model

Mesoscopic and macroscopic hydromechanical lattice simulations are performed for studying the tension stiffening behavior, the change in permeability, and their linking of a tensioned reinforced normal strength concrete (NSC) member. In the lattice framework, the hydromechanical coupling is carried out by dual Delaunay triangles and Voronoi polygons, where transport elements are placed along the edges of the Voronoi polygons while mechanical elements are edges of Delaunay triangles. At the mesoscale, concrete is considered as a constitution of three phases: aggregate, cement paste and interfacial transition zones (ITZ). Two mesoscopic components cement paste and ITZ, as well as the concrete at the macroscale, are modeled by a damage model including softening strain feature. The crack opening is linked to the damage variable. Fluid flow obeys Darcy’s law in the intact conduit element and Poiseuille’s law in the crack. Validation against experimental results available in the open literature for NSC tie specimens shows that both current macroscopic and mesoscopic lattice hydromechanical models are appropriated to describe the tensile stiffening and damage induced permeability of NSC reinforced by a steel bar. Mesoscopic modeling helps to get insights of the aggregate volume fraction effect.

Effect of Mn2+ Substitution into the Host Lattice of ZnO via sol–gel Route for Boosting the Dye-Sensitized Solar Cells Performance

In this study, Mn2+ ion is doped in ZnO lattice framework at 1, 3 and 5 wt % by a simple and low-cost sol–gel route to attain improved optoelectronic response. The structural investigation by XRD and Raman analysis explores the formation of hexagonal wurtzite framework with variations in lattice parameters comprising peak intensities favors the Mn doping. The extent of doping was supported by EDS analysis, while XPS confirms doping in + 2 chemical state. The optical investigation by UV–visible and PL provides prominent peaks that also specify peak shifting in order of doping level, while the significant hexagon-shaped nanoparticle (NP) formation was deduced in SEM and TEM micrographs. These proficient ZnO NPs have been deposited on fluorine-doped tin oxide (FTO) conducting glass plate by doctor-blade technique to get photoanodes. The electrical performance of these photoanodes especially photocurrent generation was investigated under standard AM 1.5 one sun illuminations. The highest photoconversion efficiency was attained for 3% Mn-doped ZnO photoanode after xanthene-based organic dye sensitization with output efficiency (η%) of 0.25% higher than 0.03% of bare ZnO. The comparable ionic radii with exactly half-filled 3d orbital simply overlap with the ZnO valence bond responsible for enhanced overall structural and optical properties that beneficial for DSSCs performance.

Characterization of the Ammonium Bending Vibrations in Two-Dimensional Hybrid Lead-Halide Perovskites from Raman Spectroscopy and First-Principles Calculations

The facile synthesis and electronic properties of two-dimensional hybrid organic-inorganic perovskites (2D HOIPs) make these self-assembled systems an important class of energy materials. The basic building blocks of these materials include inorganic lattice frameworks that often consist of lead-halide octahedra and organic molecules possessing ammonium functional groups. Understanding the coupling between the inorganic and organic layers is key to unraveling how the electronic properties of 2D HOIPs relate to their structures. In this work, we leverage Raman spectroscopy measurements and first-principles calculations to characterize the Raman-active modes in four 2D HOIPs: hexylammonium lead iodide [(HA)$_2$PbI$_4$, HA = C$_6$H$_{13}$NH$_3^+$], hexylammonium lead bromide [(HA)$_2$PbBr$_4$], butylammonium lead iodide [(BA)$_2$PbI$_4$, BA = C$_4$H$_9$NH$_3^+$], and benzylammonium lead iodide [(BNA)$_2$PbI$_4$, BNA = C$_6$H$_5$CH$_2$NH$_3^+$]. We focus on the 1400-1600 cm$^{-1}$ range where the Raman intensity of the molecular constituents is the strongest, and assign the major peaks observed in experiments as ammonium bending vibrations. We employ a combination of density functional perturbation theory based on the local density approximation and the frozen-phonon approach based on the vdw-DF-cx functional to find quantitative agreement between experimental and calculated Raman spectra. Furthermore, by comparing the vibrational spectra of isolated molecular cations with those near lead-halide clusters, we show how the inorganic lattice framework modulates the vibrational properties of the organic cations. We conclude that the properties of the Raman-active ammonium bending modes could effectively probe the local microscopic structure of the inorganic lattice framework in 2D HOIPs.